Anyone who swapped a daily soda for seltzer and then read a scary post about carbonation ruining teeth has been waiting for a direct comparison. A small study presented this week offers one, and it favors the sparkling water.
Researchers at Purdue University measured how mouth acidity changed in 20 adults after they drank sugar-sweetened soda, regular unsweetened sparkling water, calcium-fortified sparkling water, and plain water. Soda produced the largest and longest drop in salivary pH. The sparkling waters caused a temporary dip that saliva corrected, and acidity stayed above the level associated with enamel damage.
The measurement here is oral pH, which is a proxy for erosion risk rather than a measurement of erosion. No teeth were examined. That is the appropriate frame for a household deciding what to keep in the fridge: this is useful supporting evidence for a swap many people have already made, not a settled answer about long-term dental outcomes.
What the Researchers Measured
Tooth enamel begins to dissolve when the mouth's pH falls below roughly 5.5. That threshold is well established in dental research and is the benchmark the study used.
The team tracked salivary pH in real time after each beverage rather than simply testing the acidity of the drinks in a bottle, which is the more common and less informative approach. What happens in the mouth depends on saliva, which buffers acid and restores neutral conditions over minutes.
Sugar-sweetened soda drove salivary pH significantly lower than the other drinks and kept it there longest. The sparkling waters lowered pH too, but less, and saliva brought conditions back before crossing the erosion threshold.
Wajiha Zulfiqar, a graduate student in nutrition science at Purdue who presented the work with Cordelia A. Running, PhD, said that "unsweetened sparkling water may be a lower-risk alternative to soda," adding the qualifiers that it be consumed in moderation and alongside good oral hygiene.
Why pH Is a Proxy and Not a Damage Measurement
The limitations belong next to the finding rather than at the bottom, because they change how much weight it carries.
Twenty participants is a small sample. The study appears to capture a single exposure per beverage rather than the repeated daily sipping that actually drives erosion in real life. It measured a chemical condition in saliva, not enamel hardness, mineral loss or clinical erosion, and it followed no one over time. The work was presented as a conference abstract at NUTRITION 2026, selected by an expert review committee but not peer reviewed for journal publication. Funding sources and conflict-of-interest disclosures were not included in the materials reviewed for this article.
There is also a mechanism this study did not address. Soda threatens teeth two ways: acid erodes enamel directly, and sugar feeds the oral bacteria that produce acid and cause cavities. Salivary pH after a single drink captures part of the first pathway and none of the second. The full advantage of unsweetened sparkling water over soda is therefore probably larger than this measurement alone shows, but for a reason the study did not test.
What Dentists Already Knew About Acidic Drinks
None of this is new territory for dentistry. Erosion from acidic food and drink is well documented, and unlike a cavity it does not heal. Once enamel is gone, it does not grow back, and the exposed dentin beneath it is yellower and more sensitive.
Research published by the American Dental Association has examined flavored and plain sparkling waters alongside soda by soaking extracted teeth, finding that acids in sugar-free beverages can erode enamel. Edmond Hewlett, DDS, an ADA spokesperson, summarized the principle: "The more acidic the drink, the greater the risk of tooth erosion."
Two practical implications follow. Flavored sparkling waters, particularly citrus varieties and anything with added juice or acid, are more acidic than plain carbonated water and should not be assumed equivalent. And frequency matters more than volume, because each exposure restarts the acid clock. A can sipped across three hours is harder on enamel than the same can finished in ten minutes.
Practical Steps That Do Not Depend on This Study
The advice that follows from decades of dental evidence, not from a single preliminary abstract, is straightforward.
Drink acidic beverages with meals rather than continuously through the day, since saliva production at mealtimes helps buffer acid. Use a straw, which reduces contact between the liquid and the front teeth. Rinse with plain water afterward. Choose plain unsweetened sparkling water over flavored versions when the goal is minimizing acid, and treat plain still water as the option with no erosion risk at all.
People who should be more careful include anyone with acid reflux, dry mouth from medication or medical treatment, existing enamel wear or sensitivity, and those in orthodontic treatment. Persistent tooth sensitivity to cold or sweet, visible thinning or translucency at the edges of front teeth, or teeth that look increasingly yellow are reasons to see a dentist rather than adjust beverages and hope.
What Happens Next
The Purdue team says it plans to study the longer-term effects of sparkling water on oral health, including whether it changes other features of the mouth environment that matter for teeth and gums. Publication in a peer-reviewed journal would allow the methods and statistics to be evaluated properly.
The confirmed finding is that in 20 adults, sugar-sweetened soda lowered salivary pH more and for longer than unsweetened sparkling water did, with the sparkling waters staying above the erosion threshold. The people most affected are frequent soda drinkers considering a switch, and anyone with existing enamel wear. The most reasonable action is the ordinary one: limit acidic drinks to mealtimes, use a straw, and keep regular dental visits. The central uncertainty is what any of this means over years, which a single-session pH study cannot address.
Frequently Asked Questions
What did the study find? In 20 adults, sugar-sweetened soda produced the largest and longest drop in salivary pH. Unsweetened sparkling waters caused a smaller, temporary dip that stayed above the level associated with enamel damage.
Has this been peer reviewed? No. It was presented as an abstract at NUTRITION 2026. Abstracts are selected by an expert committee but have not undergone the peer review required for journal publication.
Does this prove sparkling water is safe for teeth? No. The study measured mouth acidity after drinking, which is a proxy for erosion risk. It did not measure enamel, and it did not follow anyone over time.
At what point does enamel start to dissolve? Dental research places the threshold at a mouth pH of about 5.5. Below that, acids begin to dissolve enamel.
Are flavored sparkling waters the same as plain? No. Flavored versions, especially citrus, and anything with added juice or acid are more acidic than plain carbonated water and should not be assumed equivalent.
What can people do to reduce risk? Drink acidic beverages with meals rather than sipping all day, use a straw, rinse with plain water afterward, and keep regular dental checkups. Plain still water carries no erosion risk.
When should someone see a dentist? Persistent sensitivity to cold or sweet, visible thinning or translucency at the edges of front teeth, or teeth that appear increasingly yellow warrant a dental evaluation.
